In many systems, such as, e.g., 802.11 based Dedicated Short Range Communications (DSRC) Wireless Access Vehicular Environment (WAVE) systems, a device may be required to operate simultaneously in two or more bands. In DSRC, 7 channels of 10 MHz each have been defined for vehicular use. One of these channels is deemed to be a “safety-only” channel. In DSRC, it is proposed that a vehicle may operate two radios simultaneously; one radio is reserved purely for sending and receiving safety related messages in a safety channel (Channel 172) while another radio is used for non-safety related applications in one of the other 6 channels.
Since the two radios within a device are very close to each other and may also occupy adjacent channel spectrum, the energy spilled over from transmissions on channel B to channel A may be significantly higher than the thermal noise level in channel A. In such a scenario, the interference may significantly affect the PHY layer and medium access process (MAC) of radio A. For example, the radio A might detect channel A (i.e., the medium) as busy when radio B is on even though channel A was actually available and hence not decrease its back-off counter.
The interference may also make signals transmitted on channel A by other devices to radio A undetectable. Simultaneous transmit and receive on physically adjacent channels is avoided in many systems because of this co-interference problem. In view of the above discussion, it should be appreciated that there is a need for new and/or improved methods for reducing and/or eliminating the effect of self-interference from transmissions from a transmitter of a device which also includes a receiver subject to interference from the device's transmitter.